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Querying Data

  • Straipsnis

Entity Framework Core uses Language-Integrated Query (LINQ) to query data from the database. LINQ allows you to use C# (or your .NET language of choice) to write strongly typed queries. It uses your derived context and entity classes to reference database objects. EF Core passes a representation of the LINQ query to the database provider. Database providers in turn translate it to database-specific query language (for example, SQL for a relational database). Queries are always executed against the database even if the entities returned in the result already exist in the context.

Tip

You can view this article's sample on GitHub.

The following snippets show a few examples of how to achieve common tasks with Entity Framework Core.

Loading all data

using (var context = new BloggingContext())
{
    var blogs = context.Blogs.ToList();
}

Loading a single entity

using (var context = new BloggingContext())
{
    var blog = context.Blogs
        .Single(b => b.BlogId == 1);
}

Filtering

using (var context = new BloggingContext())
{
    var blogs = context.Blogs
        .Where(b => b.Url.Contains("dotnet"))
        .ToList();
}

Further readings